Which of the following statements is false?
Correct Answer: A. Workability decreases with increase in moisture content
📚 Detailed Explanation: Identifying the False Statement
Why A is FALSE (= the answer): Statement A says “workability decreases with increase in moisture content” — this is the opposite of the truth. Increasing moisture (water) content increases lubrication between particles, reduces internal friction, and increases workability. This is fundamental: workability is directly proportional to water content (at a given cement and aggregate content).
Checking All Statements
| Statement | True/False | Reason |
|---|---|---|
| A. Workability decreases with more moisture | FALSE | More water = higher workability |
| B. Controlled concrete = preliminary tests done | TRUE | Standard definition per IS 456 |
| C. Bulking of sand depends on fineness of grains | TRUE | Finer sand bulks more; coarse sand bulks less |
Key Concepts
- Workability increases with water content — this is directly opposite to what statement A claims.
- Controlled concrete (IS 456): concrete designed and tested to a specified strength, with mix proportions determined by preliminary tests.
- Bulking of sand: fine-grained sand bulks more (up to 30%) due to surface tension of thin water film; coarse sand bulks less (<10%).